Specific gonadotropin receptors exist for both luteinizing hormone and follicle stimulating hormone. The mechanisms by which new plasma membrane receptor sites are induced and the fate of specific receptors after hormonal interaction are unknown. Studies will be undertaken to examine those questions. Highly purified solubilized receptors of LH and FSH will be isolated. Fluorescent labeled specific receptor antibodies will be used for localizing and quantitating specific membrane receptors. Simultaneous studies will be carried out with labeled gonadotropin to independently quantitate receptor sites available for hormonal binding. In addition, physical studies, characterizing conformational changes of specific membrane receptors, resulting from hormonal interaction, will be carried out. Cyclic AMP-dependent protein kinases are present in the ovary. Evidence suggests that cAMP-dependent protein kinases mediate both FSH and LH (hCG) action. Preliminary evidence suggests that cAMP-dependent protein kinases finely modulate both FSH and LH action. The specific substrate for phosphorylation by protein kinases is unknown and will be defined. In addition, the fate of the activated catalytic subunit will be examined to ascertain whether that subunit is translocated to another part of the cell or is inactivated in situ by specific inhibitors. Immunological and biochemical analysis of the regulatory and catalytic subunits of protein kinases will be carried out to ascertain whether identical protein kinases modulate both LH and FSH activities. Basic information provided in these studies should form a basis for studying new methods altering ovulation and corpus luteum formation potentially leading to new methods for population control.